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Carotid artery plaque assessment requires more than one imaging modality

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Full assessment of carotid artery plaques requires more than one imaging modality, say researchers from the Netherlands.

“Positron emission tomography (PET) imaging allows the assessment of plaque inflammation, but needs to be combined with a computed tomography (CT) or magnetic resonance imaging (MRI) scan to assess other plaque features, such as lipid-rich necrotic core size,” Dr. M. Eline Kooi from Maastricht University Medical Center told Reuters Health in an email.

Dr. Kooi and colleagues compared 18F-fluoro-2-deoxyglucose (FDG) PET, CT, and MRI assessments of carotid artery plaque in 50 patients with symptomatic carotid atherosclerosis.

PET measurements did not correlate with CT/MRI-assessed parameters, the authors report in the December Stroke.

18F-FDG PET standard uptake values were significantly higher in plaques with intraplaque hemorrhage, but did not differ between plaques with an intact or thick fibrous cap and plaques with a thin or ruptured fibrous cap on MRI.

Minimum lumen diameter and vessel wall volume did not differ significantly as measured by CT and MRI, the researchers note, but volume of lipid-rich necrotic core and calcifications were larger on CT, whereas volume of fibrous tissue was larger on MRI.

“18F-FDG PET scan is not interchangeable with an MRI/CT scan,” Dr. Kooi concluded. “Correlations between CT and MRI measurements are moderate to strong, but there is considerable variation in absolute differences.”

“Future prospective longitudinal studies should determine which imaging modality is most effective in predicting a future stroke and thus in improving patient selection for surgery,” Dr. Kooi said. “These studies have not yet been performed and thus the favorite modality cannot yet be chosen.”

“Carotid plaque imaging has great potential for improved stratification of patients with carotid plaque for surgery or stenting and for the assessment of new drug therapies,” Dr. Kooi added.

Stroke 2009;40:3718-3724.